It depends on the purpose. If you want to teach a language for the purposes of Teaching languages, then Racket is unmatched. It’s not the most useful in the Industry, but it can teach you how, well, pretty much every single other language pattern works, from dynamic to typed to procedural to functional to OOP and all. You will make someone a better programmer overall in any language by teaching them the bulk of racket and it’s patterns.
If you are going to do web-work, then I’d say Rust or Elixir, depending.
For heavy CPU work, Rust, just outright, don’t even consider C/C++ anymore.
For whatever other purpose it all depends.
But yes, for a teaching language, teach Racket.
I voted for Rust only because it’s the more overall useful, but Racket is what I’d choose as a teaching language by far, but it wasn’t an option.
And if I am getting really picky I will say there is no lisp. Clojure is not a real lisp.
Go Racket.
CommonLisp is pretty awesome overall though, it’s a kitchen-sink language by far. Can be useful to learn it instead but then you’ll be learning it’s ecosystem instead of the ‘patterns’ that Racket more focuses on. ^.^